Monday, May 7, 2018

Energy: "Thorium salt reactor experiments resume after 40 years"

From New Atlas:

Scientists at the Nuclear Research and Consultancy Group (NRG) the
Netherlands, are looking back to the 1970s to meet the energy needs of
the future. For the first time since 1976, the NRG team is conducting
experiments in thorium
molten salt reactor technology that could lead to cleaner, safer
nuclear reactors capable of supplying energy on a global scale.

In a world marked by strong political
pressure to create a carbon-neutral economy, nuclear energy seems like
an ideal alternative. Despite their reputation, nuclear reactors have a
remarkable record for reliability, produce carbon emissions that are
lower than even wind and solar when construction, operation, and life
cycles are taken into account, and have the lowest fatality rate per
watt of any competitor.

However, nuclear power does
suffer from four major drawbacks. First, the uranium needed to power
reactors is rare and expensive to process. Second, the technology to
produce nuclear fuel can also be adapted to create weapons. Third, there
is the danger in older reactor designs of an unlikely, but frightening
catastrophic meltdown. And fourth, no one has come up with a long-term
nuclear waste disposal strategy that is acceptable to everyone.

One way of overcoming these issues is
to replace the uranium and the plutonium derived from it with a
different fissile material. Since the 1940s, the most attractive
alternative has been thorium. Unlike uranium, thorium is abundant and
widespread, it doesn't require the sort of elaborate enrichment process
that uranium needs, and it isn't easily made into bombs. In addition,
thorium reactors have an inherently safe design that shuts down if the
reaction goes out of control, and the radioactive waste products from
thorium are relatively short lived – becoming harmless in only a matter
of centuries.

The main obstacle is that
thorium can't achieve critical mass on its own. If you take enough
uranium that's been refined to fuel grade and stack it together, the
amount of neutron radiation released will start a chain reaction that
will cause the uranium atoms to split in a self-sustaining process.
Unfortunately, thorium can't do this, so thorium fuel must be mixed with
uranium or subjected to an outside neutron source to start the reaction
cycle....MUCH MORE